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Anemia - B12 deficiency

  • Definition

    Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues.

    Vitamin B12 deficiency anemia is a low red blood cell count due to a lack of vitamin B12.

    See also:

    • Megaloblastic anemia
    • Pernicious anemia

    Alternative Names

    Macrocytic anemia


    Causes, incidence, and risk factors

    Your body needs vitamin B12 to make red blood cells. In order to provide vitamin B12 to your cells:

    • You must eat enough foods that contain vitamin B12, such as meat, poultry, shellfish, eggs, and dairy products.
    • Your body must absorb enough vitamin B12. Your body uses a special protein, called intrinsic factor, released by cells in the stomach. The combination of vitamin B12 attached to intrinsic factor is absorbed in the last part of the small intestine.

    A lack of vitamin B12 in the diet may be due to:

    • Eating a vegetarian diet
    • Poor diet in infancy
    • Poor nutrition during pregnancy

    A number of problems can make it difficult for your body to absorb enough vitamin B12:

    • Chronic alcoholism
    • Crohn's disease, celiac disease, infection with the fish tapeworm, or other problems that make it difficult for your body to digest foods
    • Pernicious anemia, which occurs when your body destroys cells that make intrinsic factor. Intrinsic factor is needed to absorb vitamin B12.
    • Surgeries that remove certain parts of your stomach or small intestine, such as some weight-loss surgeries
    • Taking antacids and other heartburn medicines for a long period of time